Process and apparatus for producing a pulverulent building material



Aug. 2; 1938.

A. SOMMER I ROCESS AND APPARATUSFOR PRODUCING A PULVERULENT BUILDING MATERIAL Filed March 24, 1937 2 Sheets-Shet 1 9441/6/76; MMJarmv-pQ A. soMivlER Aug. 2; 1938;

PROCESS AND APPARA TUS FOR PRODUCING A PULVERULENT BUILDING MATERIAL 2 Sheets-Sheet 2 Filed Marh 24, 19:57

Patented Aug. 2, 1938 "umrao sTA E s PATENT OFFICE r 2,125,860 raocass AND APPARATUS roe raonuo lNG 'A PULVEBULENT- BUILDING MATE- RIAL Albert Sommer, Zurich,

the firm Straba Switzerland, assignor to Strassenbaubedarfs-Ak- ,tlengesellschaft, Zurich, Switzerland Application 14 Claims.

.verulent constituent is atomized in i a mixing chamber inform of a mist or cloud and mixed with a mist or cloudof fluid or liquefied constituents, the particles of the different constitu-v ents being thereby caused to settle on one another, as a result of which a pulverulent mixture is obtained as final product.

f .To utilize the process for bituminizing a filler (i. e., a pulverulent or fine grain .mineral substance) to be adapted for building purposes, particularly for road construction, a relatively large quantity of liquefied constituent, such as bitumen, must be incorporated in the pulverulent mineral substance. This I found. entails difliculties, since the liquefied constituent'has the. tendency to form lumps when precipitated immediately after mixing.

This'invention, therefore, has for its object to provide a process and means which will obviate these difliculties and whereby it will be possible to more effectively utilize my atomiza-- tion process in instances when relatively high percentages of fluid or liquefied constituents are employed. This is accomplished by directing a current of air onto the atomized particles while in a state ofsuspension, which is adapted I wherein the different clouds are to .grip the aggregates of the mixture at the point of their injection and to carry the mixture through centrifugal dust separators. V

i This current of air may, when necessary, be. cooled, so as to cool the aggregates during the mixing action. In this manner the particles of the mixture before they have time to settle down, are held in suspension and cooled by the air current, preferably produced by suction, long Y enough to lose their stickiness and are thereby prevented from conglomerating, rendering the mixture perfectly fit for storing until put to use, when, by pressure, heating or otherwise, the binding property of the mixturecan be restored. To carry out my new process I employ an apparatus which in principleis known but which for the purposes of the present invention has certain novel features.

With the known apparatuses of this kind the pulverulent substance is injected by a nozzle into amixing chamber by compressed air, whereby it is atomized into the form of a mist or cloud. At. the same time fluid or liquefied substances are similarly atomized in the mixin"g chamber,

caused to become intimately mixed with one another, and from which the final mixture, after settling Tperature.

March 24, 1937, Serial him-132,729 In.Germany July 25, 1936 down in thechamber, is dropped out through the openings in the bottom of the mixing chamber.

According to this invention, my apparatus comprises in addition to the means hereinbefore mentioned, controllable inlet passages for thesubstances to b'e'atomized, and means whereby an air current is caused to grip the mixture to hold the 'particles thereof in a state of suspension, and to carry off said mixture through suitable centrifugal dust separators in which it is separated from the air.

The apparatus also comprises suitable cooling means whereby the mixture maybe cooled dur-.

ing the mixing period and other improvements which will be more fully described hereinafter. In the accompanyingdrawings which form part of this specification and in which similar reference characters denote corresponding parts:

Fig. 1 is a diagrammatic elevation of one embodiment of the apparatus used for carrying out my process; 7

Fig. 1a is a diagrammatic showing of the bitumen heater and pipes;

Fig. 2 is a top plan view thereof; Fig. 3 is an enlarged sectional the bitumen atomizing nozzle;

Fig. 4 is a cross section thereof;

elevation of Fig. 5 is'a vertical section of a feeding device for the pulverulent constituents; and

Fig. 6 is a vertical section thereof at a right angle to Fig. 5.

I denotes a bitumen heater from which leads a pipe 2 into a bitumen pump 3. From the latter the bitumen is conveyed through a pipe 4 to an intermediate receptacle 5 in which, as will be presently described, through a circulating system the bitumen is maintained at constant tem- Leading from this receptacle is an overflow pipe 6 which is connected to a return pipe 1 leading into the heater l. Contrary to the hitherto known construction, the intermediate receptacle is arranged at a higher eleva-- tion than the injection nozzle, so that the bitumen may flow by its own gravity into the nozzle, instead of, as hitherto, being forced down by compressed air which often causes disturbances. II

A pipe 8 leads from the intermediate receptacle ,5 into the bitumen atomizing nozzle l0 carried by the nozzle casinglll. This pipe 8 is connected to a mouthpiece ll of the bitumen atomizing nozzle I0, as will behereinafter more fully described. I! is a motor which serves to drive an air compressor l3. An air tube l4 leads from compressor 13 through an oil separator l5 into the air heater Hi and a tube l1- leads from said air heater l6 into the nozzle casing Sand is connected to the mouthpiece IB of said bitumenatomizing nozzle Ill.

The bitumen is sucked up by means of pump 3 from the bitumen heater i through pipe 2 and led into the intermediary receptacle 5 through pipe 5. A portion of the bitumen flows through the overflow pipe5 and the return pipe 1 back into the bitumen heater I, while another portion thereof flows through-pipe 5 to the nozzle I 5 in which the atomization is eilected.

' By usingthe overflow pipe 5 and the return pipe I, not only is a continuous circulation of the bitumen afforded; but both the temperature of the latter and the pressure with which it'is discharged from the receptacle 5 are held constant.

By preheating the air in the air heater l5 the atomization of the bitumen is greatly enhanced.

The pulverulent constituent is charged into a funnel-shaped receptacle l9 at the lower end of which is provided a feeder 20, the construction and operation of which will be hereinafter fully described and whereby the pulverulent constituent is uniformly fed into a funnel-shaped receptacle, 2| mounted below the same, to be passed therefrom to the compressed air nozzle'22. One or more compressed air nozzles 22 carried by the nozzle casing 9 are adapted to atomize the pulverulent constituents discharged from the receptacle 2l'. The nozzles i5 and 22 for the bitumen .and pulverulent substances, respectively, are

spaced according to the requirements so that the atoms or minute particles of the atomized pulverulent and bituminous substances become intimately mixed, or settle upon one another. This mixing action also continues in the chamber 23. At the bottom of said chamber are provided a number of suction funnels 25, 24, 24", 25", from which lead suction pipes 25, 25', 25", 25", into a common pipe 25, which latter communicates through'passages 21, 25, with centrifugal or similar dust separators 29-, 30, of well known construction. a

- In the present example two dustv separators are provided, although the number is optional, depending uponthe size of the plant. In'these dust separators the air is separated, in well known manner, from the dust particles of themixtu're and the latter allowed to sink to and accumulate at the bottom, from which the mixture, through vP pes 3|, 32, and sluices 33, 34, is discharged into bags 35, (Fig. l) The separation of the mixture particles from the air cannot be effectively accomplished by means of filters or like separators because of the tendency of the particles to clog therein. Nor are electric separators practical because of the relatively high cost thereof. I have found that the well known centrifugal dust separators are most advantageous for the purpose of The dust separators 23 and 35 may be jacketed for cooling purposes so that the aircirculating therethrough may be eifectively cooled. The air freed from the particles of the'mixture enters the conduit 31 communicating with the- Ilpper ends of the'separators 25 and 35 and which conduit may also be jacketed for cooling purposes. This conduit 31 is connected to the suction end of a blower 35 which is adapted to suck up'the air and return it to the chamber 23 through a pipe 55 which too may be suitably cooled. This pipe terminates in the mixing chamber 23 at 4| (Fig. 2) close to the point at which the constituents are atomized by their respective nozzles, so that the current of cooled air strongly agitates the clouds. Branching ofl theconduit 31 is a pipe 52 which communicates with the suction end of a second blower 53 by which the sucked up air is forced through a pipe 55 into another dust separator 55. From thelatter the air is then allowed to pass out through an outlet 55. Such particles of the mixture, that may still be present in the air are discharged from said separator 41 through a sluice 55 into the funnel I 5 receiving the pulverulent constituent.

A motor 49 drives the blowers a and u. A motor 50 drives the pump 3 through belt 5| and pulley 52. The motor is operatively connected by belt. 53 and pulley 54 to a diil'erential gearing 55, which by sprocket gear 55, chain 51 and sprocket gear 55 drives the feeder 25. The shaft 19 of said feeder car'ries' another gear 55, which by chain ii and sprocket wheel 52 operates the sluice 45.

The construction of the bitumen atomizing nozzle III is shown in detail in Figs. 3 and 4.

This nozzle substantially comprises a cylindrical casing 53 provided with an inlet mouthpiece H for the admission of bitumen, and an inlet mouthpiece I 5 for the admission of compressed air. Extending longitudinally through said casing is a tubular body 55 in which is home the needle valve 56 of the nozzle. This tubular body 55 is threadedly mounted in'a threaded bore provided at the upper end of said casing. The lower end of said body 55 projects through the lower open end of the casing 53. Mounted around the body 55 between mouthpieces ii and i5 is a cup-shaped body 51 carrying suitable packing means. The

upper end of the body 55 is provided with a headpiece or flange 55 by means of which the same can be screwed up or down within the casing 53, so that. by an adjustment of the annular cross sectional area of the space 15 provided between the lower end of the casing 53 and that discharge of air may of the tubular body 55, the be controlled. The body 55 can be secured in position within the casing 53 by a nut 1| workingon the threaded end of the body 55. The latter is also provided longitudinally with internal thread in which works the needle valve of the nozzle, which thus can be raised and lowered to vary the annular space 15 .between the conical tip 13 of the needle valve 55 and the'conical inner wall of body 55. Thus, by adjusting the needle valve 55 longitudinally, the size of the opening through which the bitumen is discharged can be varied. The needle valve 55 is provided.

with a serrated head or knob 55' whereby it can be manipulated. Working on said needle is a nut 12 for tightening the'same in adjusted position.

The packing cup 51 is provided with a plurality of narrow slits 13 extending tangentially relative to the annular channel 15 formed between the body 55 and the walls of the cup 51. The compressed air entering through mouthpiece l5 passes through the slits 13 provided in said cup 51 into the annular channel 14 (Fig. 4) and thence to the annular discharge passage 15 which surrounds the bitumen discharge e 15. The slits being arranged tangentially relative to channel 15 impart to the current a whirl,-

lmr motion, thereby enhancing the atomization of the bitumen.

The bitumen admitted through the mouthpiece ll enters through openings 55* the tubular body 55. The needle valve 55 is provided at its lower part with a plunger-like shoulder 11 in which are formed slots 15 leading into the discharge chamber 15. These slots 15, as will be seen, are biased so as to impart to the bitumen as it is beingdischarged a twisting motion. The plunger-shaped shoulder 11 also serves to prop die valve 56 in the tube 65.-

In order to keep the charge of thepulverulent constituent always constant, the funnel I 9 into Laterally of said cylinder 20 are provided guards 8|, 82, hinged to ,the bottom of said funnel l9 and which are adapted to be pressed against said cylinder 20 by springs 85, 86. The pulverulent material dropping into the channels 80 will be carried along with the cylinder 20 whenthe latter is rotated and prevented from leaving said ,channels as long as the latter are within'the range of the guards BI, 82. These channels are so arranged on the cylinder 20 that the channels will empty successively one after the other. By the particular arrangement of the channels and guards (Fig. 6) a gradual discharge of the material from the drum can be effected. It is ob- 'vious that instead of slanting the channels 80 on the drum, as shown, the lower edges of the guard members may beslanted.

The aircapacity of the auxiliary circulating system 42, 43 and 44 is so chosen, that the volume of air withdrawn from the main circulating system is about equivalent to the volume of injected compressed air.

It is clear that various changes may be made in the construction of the apparatus for carrying out my new process without departing from the principle of my invention. I, therefore, do not wish to restrict myself to the details of the construction described and shown.

What I claim is:

1. A process of producing a pulverulent building material from pulverulent and fluid or liquefied base constituents, consisting in the atomization in a mixing chamber of each of said constituents separately and simultaneously into mists orclouds, impinging upon the atomized particles near the point of their injection into said chamber while still in a state of'suspension a cool air current and carrying. the mixture through dust separators.

2. A process according to claim 1, in which the mixture is subjected to the action of a suction produced circulating air current. 3. A process according to claim 1,'*in which the air freed from dust particles of said mixture in said dust separators is passed back into the mixing chamber to act on the constituents at the point of their injection. I

4. In a process according to claim '1, in which the atomization of said bituminous substance is enhanced by imparting to said substance and the compressed air acting thereon twisting or whirling motions.

5. In an apparatus for producing a pulverulent building material from a pulverulent conthe controllable means for feeding the pulveru--v lent material includes a revolving cylinder havin channels to receive said material and means for causing a gradual uniform discharge of said material from said channels while said drum is 'rotated.

7-. In an apparatus of the character described, means for atomizing a bituminous substance, in-

cluding a heater for said substance, a pump, an auxiliary receptacle arranged above the level of said atomizing means, an overflow leading from said receptacle to said atomizing means and a return conduit leading from said receptacle into said pump, whereby said substance is caused to circulate through said receptacle to maintain the molten substance in saidreceptacle at constant level and temperature.

8. In an apparatus according to claim 5, in which suction means communicate with said mixing chamber and lead into said mixture separating means. i l l a l 9. In an apparatus according to claim 5, in which said mixture separating means include dust separators, a suction effected air circulating system, including means for carrying said mixture from said'mixing chamber into said sep arators, and means for returning the air from said separators into said mixing chamber.

10. In an apparatus according to claim 5, in which is 3 provided an auxiliary suction efiected air circulating system, including an auxiliary dust separator having an air discharge, auxiliary suction creating means and means for carrying 11. In an apparatus of the character described,

an atomizing nozzle for a fluidor liquefied substance comprising acasing formed with separate mouthpieces for the admission of said substance and compressed air, an adjustable tubular body extending through said casing and an adjustable needle valve extending through said tubular body, the mouthpiece for said substance leading into a discharge channel formed between said needle valve and said tubular body, and the mouthpiece for said compressed air leading into a dischargechannel formed between said tubular body and said casing. I V

12. In an apparatus according to claim 11, in which means-for feeding said fluid or liquefied substance from its said mouthpiece into its discharge channel are provided which include slanting ducts adapted to impart to said substance a twisting motion.

13. In an apparatus according to claim 11, in which means for feeding the compressed air from its mouthpiece into its discharge. channel are provided whichinclude ducts extendingtangentially relative to said channel and adapted to impart to said air a; whirling or cyclonic motion.

14. In an apparatus according to claim 11, in which packing means are provided in said casing comprising an adjustable cup Iormed with ducts extending tangentially relative to the compressed air discharge channel adapted. toimpart to said air a whirling or cyclonic motion.

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